Nourishing a market: a WasteCap Wisconsin project recycles gypsum drywall into fertilizer.

At the Royster-Clark Inc. fertilizer plant in Madison, Wis., the plant manager raises an inspection hatch on a product mixer and dips his hand into a stream of cascading granules. He inspects the material closely, looking at the color and consistency, rolling the granules between his fingers to check their texture, then smiles and holds his hand out for others to see the material.

"That's a good product;" he says enthusiastically. "We can sell that."

At the far end of the production line, Sulfa-Cal, Royster-Clark's brand name for a fertilizer that has gypsum as a main ingredient, waits to be packaged and sold as a product that provides 20 percent calcium and 17 percent sulfur for cranberries, potatoes and a variety of other crops in the Midwest.

At the beginning of the production line was a pile of gypsum derived from scrap drywall. It was the successful culmination of work by WasteCap Wisconsin, Royster-Clark and many others testing whether scrap drywall could be used as a source for gypsum in the manufacture of fertilizer.

BACKGROUND. In 2001, WasteCap Wisconsin, a nonprofit organization based in Milwaukee that provides waste reduction and recycling assistance for businesses, provided waste management services during the construction of Alliant Energy Corporation's worldwide corporate headquarters in Madison, Wis. Part of the project involved finding a recycling market for its drywall scrap. WasteCap opted for land application of the drywall to agricultural fields. Gypsum drywall compares favorably with agricultural gypsum in its chemical composition, according to a study by R.F. Korcak at the USDA Agricultural Research Service.

However, it became apparent that the need for agricultural gypsum in the immediate vicinity is far less than the generation of scrap drywall. The question became whether there was another use for scrap drywall, perhaps as a component in another product, that would increase its value and demand.

WasteCap Wisconsin conducted research into the uses of scrap drywall. It was greatly aided in this effort by a drywall recycling bibliography compiled by John Reindl, the Dane County, Wis., Recycling Coordinator. This research revealed that gypsum was a vital ingredient in many manufactured fertilizers and that a fertilizer manufacturing plant operated by Royster-Clark, a large national producer and distributor of agricultural chemicals, was located in Madison, Wis.

The Royster-Clark plant produces 50,000 to 70,000 tons of fertilizer products annually, at times purchasing 5,000 tons of agricultural gypsum yearly as an ingredient in those products. It is estimated that 3,000 to 5,000 tons of waste drywall are generated each year in Dane County, the county in which Madison is located.

WasteCap Wisconsin approached Ken Breezer, Royster-Clark's plant manager, to see if he would be willing to conduct a test to determine if gypsum derived from scrap drywall could be substituted for agricultural gypsum in its manufacturing process. Breezer was intrigued by the idea that his plant could receive a high quality raw material for a lower price than it was currently paying while also benefiting the environment and the community. He was willing to try it.

With that assurance of cooperation, WasteCap Wisconsin applied for and received a Solid Waste Management Assistance Grant from the U.S. Environmental Protection Agency to help fund the project.

COLLECTION. Royster-Clark needed a minimum of 20 tons of gypsum to conduct proper manufacturing tests, but it preferred to receive 50 tons. This amount would allow the company to test different products and processes and to give it a better idea of how to best use the material.

WasteCap identified two sources for scrap drywall. Between February and June of 2003, First Choice Drywall collected 62 tons of scrap drywall from the Overture Center for the Arts construction site by J. H. Findorff & Son and from Don Simon Homes (now Veridian Homes) construction sites. Pellitteri Waste Systems donated dumpsters for storage of the scrap drywall.

STORAGE. The best available option was storing and processing the material at the Royster-Clark plant. It had many advantages. It was large--more than 17 acres--and closer to the central city than the landfill, reducing hauling distances. It had a paved area where the material could be stockpiled and was fenced so that tampering wouldn't be an issue. The plant was also adjacent to the manufacturing site, eliminating transportation costs after processing. It even had a truck scale adjacent to the site so the incoming material could be weighed.

The Royster-Clark site had one major disadvantage, however. It is located within Madison and is surrounded by a mixed residential and commercial neighborhood. The company filed an application for a beneficial reuse exemption with the Wisconsin Department of National Resources, which was issued in Feb. 2003. WasteCap Wisconsin contacted the Eastmorland Neighborhood Association and gave a presentation describing the project. Attendees felt that, while the goals of project were laudable, they were skeptical that it could be carried out without disruption to the neighbors. They were particularly concerned that stockpiled material would be unsightly and that dust from the operation would create a nuisance. Their concerns were assuaged only when WasteCap assured them that the stockpiled material would be kept covered, that no dust would be allowed to escape Royster-Clark's grounds, and that they would be welcome to observe the processing operation.

GRINDING AND SCREENING. Kevin Peterson of Construction Waste Solutions (CWS) of Minneapolis, Minn., approached WasteCap Wisconsin to offer grinding and screening services for the project. The company was developing a new horizontal grinding machine with a sealed hopper to mitigate dust when grinding drywall. WasteCap Wisconsin wanted to do whatever it could to avoid dust issues in the project, so we agreed to use the new CWS machine.

A May 9, 2003, processing date was established. To say that things didn't go as planned is an understatement. CWS arrived, not with the new grinder, but with a small horizontal grinder and a small portable trommel screen. The new grinder was not ready.

Moderate winds were blowing when CWS set up its equipment in our outdoor location. Despite extensive draping of the equipment with tarpaulins, dust from processing escaped the Royster-Clark property as Wisconsin Department of Natural Resources staff, neighbors and other observers looked on. Luckily, space was available in a large, domed storage building on the Royster-Clark property just a few hundred feet away. The operation was relocated there.

When operations were restored, it quickly became apparent that the trommel screen was inadequate. Not only was too much paper passing through the screens, but the screen was so small that the paper it removed contaminated the finished product. The operation was shut down at the end of the day, having ground a total of perhaps 4 to 5 tons of material, none of it useable because ii contained too much paper.

It was clear that we did not have the equipment to properly process the drywall and to deliver finished material that Royster-Clark could use in manufacturing its fertilizer. We then worked with Ken Patterson, Packer Industries, Mableton, Ga., who has extensive experience processing drywall for recycling. Patterson arranged with Resource Recovery Systems Inc., Hartford, Wis., to provide screens.

CWS arrived with the new grinding machine June 11 and ground the remaining 55 tons of scrap drywall. Resource Recovery Systems, during the course of two days, ran the ground drywall twice through its two-deck portable screener--the smallest screen was 1/16 inch small enough to ensure that the screens used in Royster-Clark's manufacturing process would not become clogged with paper from the drywall.

At the end of the screening process, there were four piles: a finished pile that would go to the plant; a waste pile that was mostly paper in volume but contained large chunks of gypsum; and two piles of different size gypsum granules and paper fibers. These last two piles were high-quality materials. However, hurried efforts to find markets were unsuccessful, and the materials had to be sent to the landfill.

We were able to deliver about 40 tons of finished product to the Royster-Clark plant. Two weeks later, Royster-Clark successfully used the gypsum in the manufacture of Sulfa-Cal fertilizer.

LESSONS LEARNED. For fertilizer manufacturing, the paper must be removed during the screening of the ground drywall. This is necessary because the manufacturer screens its product to clean it before it is packaged. Paper fibers left in the gypsum can clog the product screens.

The key to making this process a commercially viable operation is minimizing the handling and transportation costs and processing the material efficiently. Agricultural gypsum, the product with which drywall gypsum must compete, is inexpensive. Portable equipment is probably not suitable for use in a permanent drywall processing operation. For highest efficiency, grinding and screening operations must occur in one continuous flow, and each machine must be adjusted to maximize production.

A significant pan of the value to the manufacturer of gypsum from scrap drywall is that it is much drier than the mined agricultural gypsum it buys, which is so moist it often clumps up and sticks to the sides of feeder bins, making it difficult to maintain an even production flow in the plant.

This project experienced a 65 percent waste factor in the scrap tonnage delivered compared to what was collected. We have been told that a permanent facility would reduce the waste factor to about 25 percent. Still, a permanent processing facility should pursue markets for byproducts.

Contamination of the scrap drywall is an issue. Suppliers of scrap drywall need to be educated that wood, corner bead, electrical wire, plastic, pop cans, lunch bags and any other contamination must be eliminated.

It appears that a permanent scrap drywall processing operation can be commercially viable even in this relatively small market. Income comes from two sources: a tipping fee to drop the scrap gypsum and a charge for the screened product that is slightly less than the delivered cost of agricultural gypsum.

Moisture-resistant drywall, which was not allowed for use in this project, is an important and growing waste stream. Tests need to be carried out to determine if this material can be used in fertilizer.

A project like this needs good partners, good equipment, knowledgeable people and community support to be successful. WasteCap Wisconsin's primary partners on this project were Royster-Clark, Construction Waste Solutions, Dane County Department of Public Works, First Choice Drywall, J. H. Findorff & Son, Overture Center for the Arts, Packer Industries, Pellitteri Waste Systems, Resource Recovery Systems, U.S. Environmental Protection Agency, Veridian Homes and the Wisconsin Department of Natural Resources.

NEXT STEPS. This project was successful. WasteCap Wisconsin collected more than 60 tons of scrap drywall from commercial and residential sites, ground it, screened it and delivered it to the Royster-Clark plant, which made high-grade commercial fertilizer from it. That was the stated purpose of this project, but no one wants it to end there.

From the beginning, WasteCap Wisconsin's purpose in undertaking this project was to see if a permanent, self-sustaining market for scrap drywall could be developed in the Madison market. It now appears it can.

In April 2004, Royster-Clark conducted another manufacturing test using 100 tons of ground, screened drywall gypsum. Royster-Clark has also expressed an interest in establishing a permanent scrap drywall processing facility. If all goes well, a business plan will be produced and work on a permanent facility could begin in 2005.

Jenna Kunde is executive director of WasteCap Wisconsin and can be contacted at [e-mail]. Ralph McCall is the organization's project manager and can be contacted at [e-mail].